Making of Eiffel Tower

 
The Eiffel Tower is an iron lattice tower located in Paris. Built in 1889, it has become both a global icon of France and one of the most recognizable structures in the world. The tower is the tallest building in Paris and the most-visited paid monument in the world; millions of people ascend it every year. Named for its designer, engineer Gustave Eiffel, the tower was built as the entrance arch to the 1889 World's Fair.
The tower stands 324 metres (1,063 ft) tall, about the same height as an 81-storey building. The tower has become the most prominent symbol of both Paris and France, often in the establishing shot of films set in the city.

 

Making of Eiffel Tower

The structure was built between 1887 and 1889 as the entrance arch for the Exposition Universelle, a World's Fair marking the centennial celebration of the French Revolution. Three hundred workers joined together 18,038 pieces of puddled iron (a very pure form of structural iron), using two and a half million rivets, in a structural design by Maurice Koechlin. Eiffel was assisted in the design by engineers Émile Nouguier and Maurice Koechlin and architect Stephen Sauvestre. The risk of accident was great as, unlike modern skyscrapers, the tower is an open frame without any intermediate floors except the two platforms. However, because Eiffel took safety precautions, including the use of movable stagings, guard-rails and screens, only one man died. The tower was inaugurated on 31 March 1889, and opened on 6 May.

The 72 names on the Eiffel Tower

Gustave Eiffel engraved on the tower seventy-two names of French scientists, engineers and other notable people.

Design of the tower

Material

The pig iron structure of the Eiffel Tower weighs 7,300 tonnes while the entire structure, including non-metal components, is approximately 10,000 tonnes. As a demonstration of the economy of design, if the 7,300 tonnes of the metal structure were melted down it would fill the 125 metre square base to a depth of only 6 cm (2.36 in), assuming the density of the metal to be 7.8 tonnes per cubic metre. Depending on the ambient temperature, the top of the tower may shift away from the sun by up to 18 cm (7.1 in) because of thermal expansion of the metal on the side facing the sun.


Wind considerations

Researchers have found that Eiffel used empirical and graphical methods accounting for the effects of wind rather than a specific mathematical formula. Careful examination of the tower shows a basically exponential shape; actually two different exponentials, the lower section overdesigned to ensure resistance to wind forces. Several mathematical explanations have been proposed over the years for the success of the design; the most recent is described as a nonlinear integral equation based on counterbalancing the wind pressure on any point on the tower with the tension between the construction elements at that point.As a demonstration of the tower's effectiveness in wind resistance, it sways only 6–7 cm (2–3 in) in the wind.

Maintenance

Maintenance of the tower includes applying 50 to 60 tonnes of paint every seven years to protect it from rust.

Aesthetic considerations

In order to maintain a uniform appearance to an observer on the ground, three separate colours of paint are used on the tower, with the darkest on the bottom and the lightest at the top. On the first floor there are interactive consoles hosting a poll for the colour to use for a future session of painting.

Passenger Elevators

The original installations operated broadly on the principle of the Fives-Lille lifts.
The Fives-Lille elevators from ground level to the first and second levels are operated by cables and pulleys driven by massive water-powered pistons.
The principle behind the elevators is similar to the operation of a block and tackle but in reverse. There are 14 similar sheaves mounted statically. Six wire ropes are rove back and forth between the sheaves such that each rope passes between the 2 sets of sheaves 7 times.
The original elevators from the second to the third floor were also of a water-powered hydraulic design supplied by Léon Edoux. A pair of 81 metre long hydraulic rams were mounted on the second level reaching nearly half way up to the third level. An elevator car was mounted on top of the rams. Ropes ran from the top of this car up to a sheave on the third level and back down to a second car.
The ten-ton cars held 65 passengers each or up to four tons.
The original elevators complete with their hydraulic mechanism were completely scrapped in 1982 after 97 years of service. They were replaced with two pairs of relatively standard rope hoisted cars which were able to operate all the year round.

Restaurants

The tower has two restaurants: Altitude 95, on the first floor 311 ft (95 m) above sea level; and the Jules Verne, an expensive gastronomical restaurant on the second floor, with a private lift.

Communications
Since the beginning of the 20th century, the tower has been used for radio transmission. Today, both radio and television stations broadcast their signals from the top of the Eiffel.